Question 924108
7c = 5t - 3500
21c = {{{ 3(5t - 3500)}}}
...
21c + 15t = 37500
3(5t-3500) + 15t = 37500
30t = 37500 + 10500
30t = 48,000
t = 1,600  and c = rupees 642.86 {{{(8000-3500)/7}}}